First cannabis-based prescription drug available in US

The Food and Drug Administration in June approved the first-ever prescription drug made from cannabis. The new drug, Epidiolex, is now available by prescription in all 50 states.

» RELATED: A daily dose of cannabis could reverse effects of old age, study finds

The new medication from GW Pharmaceuticals will be used to treat two rare and severe forms of epilepsy, a neurological disorder that leads to unpredictable seizures. The oral solution is to be taken twice daily.

Epidiolex contains cannabidiol, a chemical component of marijuana. The medication does not contain tetrahydrocannabinol, marijuana’s primary psychoactive component that causes the common “high.”

» RELATED: Huge chunk of adults addicted to marijuana have anxiety disorders, many since childhood, study says

With the drug, seizures from epilepsy disorders Lennox-Gastaut syndrome and Dravet syndrome can be better controlled and “have a profound impact” on patients’ quality of life, FDA division of neurology products director Billy Dunn said in June.

"Because these patients have historically not responded well to available seizure medications, there has been a dire need for new therapies that aim to reduce the frequency and impact of seizures," CEO of GW Pharmaceuticals Justin Gover told CNN in a written statement. "We are committed to ensuring that these patients can access this novel cannabinoid medicine that has been thoroughly studied in clinical trials, manufactured to assure quality and consistency, and is eligible to be covered by insurance for appropriate patients."

» RELATED: Caught with pot? Attitudes in Georgia shift but tough laws remain

According to the company, the average list price of Epidiolex is $32,500 annually, a price reportedly in line with other branded, FDA-approved anti-epileptic drugs. GW Pharmaceuticals expects the drug will be covered by most insurance plans.

Researchers behind the drug studied Epidiolex's effectiveness in three randomized, double-blind, placebo-controlled clinical trials with a total of 516 patients, all of whom suffered with one of the two epilepsy conditions.

"In those syndromes, when [Epidiolex] was added to three other seizure [medications], on average, it reduced convulsive seizures -- or 'drop seizures' -- by about 25% to 28% compared to a placebo," Orrin Devinsky, lead investigator of two of the three clinical trials, told CNN. "So I think it's very important to recognize ... that it clearly is effective, and this was statistically significant in all three of the large studies that we did, but by the same token, the effect was modest.

“There are some people who had dramatic improvements. Many had a modest improvement, and some had no improvement,” he added. “So it's not a miracle drug. It's an effective drug, and I think its side effect profile is quite good compared to other seizure drugs that we have, but it's not a miracle cure.”

Common side effects of Epidiolex, according to the FDA, include:

The most serious risks of the drug include thoughts of suicide, aggression, panic attacks, depression (new or worsening) and agitation. Side effects may also raise possibility of rare but more severe liver injury.

Learn more about the FDA approval of Epidiolex at fda.org.